Marin Cilic’s former coach Bob Brett confirms to The Guardian that the Croatian did fail an anti-doping test.

“He said he had tested positive,” Brett said. “The one thing I found out was that he tested positive for high glucose and Marin had co-operated with the organization [the ITF] about the product and the pharmacy. One of the people in his team bought it in a pharmacy -- basically what you’ve been reading in the papers. Some people will say he made a mistake. But it was carelessness.”

The world No. 15 was said to have learned about the positive test during Wimbledon, during which he pulled out of his second-round match, citing a knee injury. He has not played since, and is said to not be doing so because he knows that a suspension is forthcoming and he might be awarded time served by sitting out.

“All through the years I’ve always explained the importance of not buying products over the counter because of the risk of contaminated products,” Brett said. “They believe that everything is going to be okay. In a sense they are naive to the risk. The player hopes it’s okay and it’s not. They are then tarnished, sponsors are reluctant to sign them to contracts and promote their products.”